Failmodes

io.github.elyngvedPublished by GitHub account elyngvedv0.1.0Updated Oct 24, 2026

MCP server for the Fail Modes taxonomy — a knowledge base of AI system failure modes

VerifiedStreamable HTTPWeb executableKnowledge & MemoryAI & ML

Overview

AI-generated overview

A read-only MCP server exposing the Fail Modes taxonomy, letting an assistant search and look up documented AI system failure modes by symptom, keyword, or ID.

What you can do
Search failure modes by symptom text or keyword phrase and get ranked matches with ID, name, category, and matched context. Retrieve the full structured record for a single failure mode by its ID slug. List all taxonomy categories with IDs, names, descriptions, and mode counts. List failure modes, optionally filtered to one category.
When to use it
Useful when reviewing, debugging, or documenting AI system behavior and you want a shared vocabulary of named failure modes (for example citation hallucination or sycophancy) to reason about problems. Handy for prompt and evaluation work that benefits from consistent terminology.
Requirements
Runs either as a hosted Streamable HTTP endpoint or locally via npx (Node.js). The local package fetches taxonomy data from failmodes.com on first tool call and caches it in memory, so internet access is required. No accounts, API keys, or environment variables are declared.
Before you install
Read-only lookup tools; no data is written, sent, or deleted. The local package and the hosted endpoint retrieve taxonomy data from a third-party site, so queries and usage reach that service. Taxonomy content is third-party reference material and should be treated as guidance, not authority.

Installation

In SourceWeft

  1. Open Failmodes in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/io.github.elyngved%2Ffailmodes/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "failmodes": {
      "type": "http",
      "url": "https://www.failmodes.com/api/mcp"
    }
  }
}

README

failmodes-mcp

MCP server for the Fail Modes taxonomy — a machine-readable knowledge base of AI system failure modes.

Provides four tools over 100+ canonical failure mode records spanning factuality, alignment, planning, code generation, instruction following, and more.

Tools

ToolDescription
search_failure_modesSearch by symptom text or keyword phrase. Returns ranked matches.
get_failure_modeRetrieve the full structured record for a failure mode by ID slug.
list_categoriesList all taxonomy categories with descriptions and mode counts.
list_modesList all modes, optionally filtered by category ID.

Quick Start

No installation required — run directly with npx:

bash
npx failmodes-mcp

Configuration

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

json
{  "mcpServers": {    "failmodes": {      "command": "npx",      "args": ["-y", "failmodes-mcp"]    }  }}

Cursor / VS Code

Add to your MCP settings file:

json
{  "mcpServers": {    "failmodes": {      "command": "npx",      "args": ["-y", "failmodes-mcp"]    }  }}

Remote (no install required)

A hosted Streamable HTTP version is also available — no npm package needed:

json
{  "mcpServers": {    "failmodes": {      "url": "https://www.failmodes.com/api/mcp"    }  }}

How It Works

On first tool call, the server fetches current taxonomy data from failmodes.com and caches it in memory for the duration of the session. Requires internet access.

The stdio transport makes this compatible with any MCP client that supports running local processes (Claude Desktop, Cursor, VS Code, etc.).

Links

License

MIT

Source: README.md at commit a20bcf3

Tools

4

search_failure_modes

Search the Fail Modes taxonomy by symptom text or keyword phrase. Returns ranked matches with id, name, category, and matched context.

Parameterssymptomrequired

get_failure_mode

Retrieve the full structured record for a single failure mode by its ID slug (e.g. 'citation-hallucination', 'sycophancy').

Parametersidrequired

list_categories

List all taxonomy categories with their IDs, names, descriptions, and mode counts.

Takes no parameters.

list_modes

List failure modes, optionally filtered to a single category by category ID.

Parameterscategory

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

100% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts